ML092090773

July 28, 2009 Meeting Slides from Entergy Operations(River Bend Station) to Discuss Ri ISI

ML092090773
Person / Time
Site:	River Bend
Issue date:	07/28/2009
From:	Entergy Operations
To:	Plant Licensing Branch IV
References
TAC ME1507, TAC ME1508
Download: ML092090773 (27)

Text

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RI lSI

Background

• RBS Submittal dated June 16, 2009

• Requested approval date - December 2010

• RF-16 begins early 2011

• RI lSI Relief Requests based upon Code Case N-716 have a common template

• Submittal template based upon Grand Gulf pilot submittal dated September 22, 2006

RI lSI

Background

• Used prior submittals as guidance in development of RBS submittal

• Followed Regulatory Guide 1.200 Revision 1 guidance

- GAPs identified

- Applicable GAPs addressed

RI lSI

Background

• Submittal consists of the following sections

- Risk Methodology based on Code Case N 716

- Risk information included

- PRA Model Capability addressed

• Performed Internal Flooding Analysis in support of submittal

RI lSI

Background

• Reviewed Risk Model for this use in accordance with current guidance

• Determined Risk Model acceptable for use in RI lSI Applications

• Assisted by industry-recognized subject matter experts

- experience with many RI lSI submittals

• Implemented latest industry guidance

• Compared with other RI lSI submittals

• Incorporated lessons learned from RAls

River Bend Station PRA

Background

• Developed in response to GL 88-20 (I PE)

• IPE approved via Oct. '97 NRC Staff Evaluation

• Used in support of various risk-informed License Amendment Requests

River Bend Station PRA

Background

• Last Full RBS PRA Revision: Revision 4 Sept. 2005

• Revision 5 update: Scheduled completion

- Dec. 2010

PRA Self-Assessment Gap Analysis

• Performed Self-Assessment cons*istent with RG 1.200 R.1 Section 4.1 in late 2008

• Assessed against RG 1.200 Rev.1 and ASME PRA Standard

PRA Self-Assessment Gap Analysis

• Used industry expertise in Gap analysis

• Entergy lead for Internal Flooding and Maintenance/Update elements

- Internal Flooding PRA performed to meet ASME Cat. II

PRA Self-Assessment Gap Analysis

• Gap: All items where any work required to meet RG 1.200 characterized as "gaps"

• Self-assessment grading consistent with RG 1.200 Section 2.1 expectations

PRA Self-Assessment Gap Analysis

• Gaps to RG 1.200 identified in submittal

- Consistent with RG 1.174

- Consistent with Vogtle

PRA Quality Per RG 1.174 section 2.2.6:

"There are, however, some applications that, because of the nature of the proposed change, have a limited impact on risk, and this is reflected in the impact on the elements of the risk model.

An example is risk-informed in-service inspection (RI-ISI). In this application, risk significance was used as one criterion for selecting pipe segments to be periodically examined for cracking. During the staff review it became clear that a high level of emphasis on PRA technical acceptability was not necessary.

Therefore, the staff review of plant-specific RI-ISI typically will include only a limited scope review of PRA technical acceptability. "

PRA Quality

• N-716 RI lSI less reliant on PRA than other RI lSI approaches

- Binning before selection

- PRA one of 5 elements

- Absolute risk ranking

• N-716 criteria

- CDF of 1E-06, LERF of 1E-07

- Degradation Mechanisms

PRA Self-Assessment

• Self-Assessment performed to identify all work to meet RG 1.200, including Cat. II, for other future risk-informed applications

• For RBS RG 1.200 Gap Analysis:

- Of the 72 Supporting Requirements (SR) with identified gaps, 7 SR's have different requirements for Cat. I vs. Cat. II.

PRA Gap Analysis

• Breakdown of gaps:

- 40 gaps: Documentation Issues

- 13 gaps: Need not be met (per EPRI) mostly uncertainty issues, would not Impact RI lSI.

- 10 gaps: Model refinements potentially needed but not significant for RI lSI

• 6 gaps (9 items): Model refinements or sensitivity studies. Addressed in Table 2 of submittal.

PRA Inputs

• Internal Flooding PRA completed June 2009

--meets Cat. II requirements

• Two cases quantified:

• Base: EPRI pipe break frequencies

• Sensitivity (Conservative, used for N-716 screening)

PRA Inputs

• Used IFPRA to assess CDF (~1 E-06) and LERF (~1 E-07) for segments considered conservative due to assumptions &

conservative simplifications due to scope

• Used PRA to confirm and provide upper limit CCDP/CLERP values in N-716 risk impact assessment

- Compared risk impact results to guidance of RG1.174

PRA Inputs

• Addressed potentially applicable gaps in Table 2 of June 16 submittal

--includes sensitivity studies

• Entered all gaps into Model Change Request (MCR) database to address in Revision 5 to RBS model

- Controlled procedurally by common Entergy process

PRA Conclusion

• Followed established process

• Determined RBS PRA providing acceptable support / sufficient rigor for N-716 RIISI

-Cat. II Internal Flooding PRA

- Gaps to ASME Std. addressed, do not impact use for RI lSI

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lSI Interval Extension

Background

• Previously extended lSI Interval to RF-15 for examination of 123 welds.

• Projected exposure for these examinations

- 17.83 Rem

• RBS proposed to perform 73 examinations by startup from RF-15

• Requested extension of lSI interval from RF-15 until RF-16 for remaining 50 examinations

lSI Interval Extension Exposure Projections

• Include weld prep time, RP, scaffolding, insulation support and NDE

• Based upon current plant conditions, and crediting previous chemical cleaning, use of shielding and system flushing

• Validated during RWP challenge process for RF-15

lSI Interval Extension Result of Approval

• Extension results in ~90% completion of subject Examination Categories for Second lSI Interval by end of RF-15

• NOTE: Subject examinations greatly reduced under RI lSI requirements

- 123 examinations under conventional lSI program

- 14 examinations under RI lSI program

lSI Interval Extension Examinations Result

• 43 examinations deferred to RF-16 pending RI lSI approval (not required under RI lSI)

• 80 examinations performed during RF-15

• No additional actions required when RI lSI submittal approved

lSI Interval Extension Conclusions

• Low significance for extension based on:

- acceptable previous examination history

- industry experience for failure probabilities

- proposed RI lSI program indicates 43 welds would not require future examination

• Excessive radiation exposure without a compensating increase in quality or safety

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